1. Field of the Invention
The present invention relates to fitting apparatus for orthotic and prosthetic devices, and more particularly to apparatus for fitting wheelchairs to persons.
2. General Background of the Invention
Wheelchairs are used by many people who, due to accident, illness or disease, have temporarily or permanently lost the use of their legs, partially or totally.
An orthosis is a brace which provides support to aid in the treatment of a physical impairment or disability. A prosthesis is a device which augments or aids performance of a natural function. A properly prescribed and fitted wheelchair is both an orthosis and a prosthesis--it provides support for an individual while increasing his mobility.
The importance of properly prescribing and fitting a wheelchair cannot be over emphasized. "The unprescribed wheelchair is potentially as harmful and as hazardous as the self-prescribed drug. It can cause trauma, secondary deformities, and disabilities and other complications which may be irreversible" (United States Department of Health, Education and Welfare, Public Health Service).
Everest and Jennings, Inc., in its booklet no. 1 Measuring The Patient, provides information on the basic measurements necessary when determining the dimensions of a wheelchair.
In the booklet, seat width is described as the first and most important dimension. Seat width is based on the measurement of the widest part of an individual's hips or thighs. The seat should be sufficient wide to distribute the individual's weight over the widest possible surface while keeping the overall width of the wheelchair as narrow as possible to minimize problems with passage through halls and doorways. If the seat width is too narrow, too much pressure may be put on the ischium and trochanters, which could cause secondary problems leading to decubiti (bed sores). Also, transfer of the individual into and out of the wheelchair will be complicated. If the seat is too wide, physical and environmental problems will be presented. For example, sitting stablity is limited, creating postural and other problems which could lead to complications such as scoliosis. Furthermore, doorways and public transportation could be made inaccessible if the seat is too wide.
Another basic dimension is seat depth. Seat depth is based on the measurement of the distance from the most posterior part of the buttocks to the back of the knee. Proper seat depth will cause the individual's weight to be distributed along the buttocks and thighs. If the seat is not deep enough, excessive pressure is created over the ischial areas, increasing the risk of decubiti. Also, the leading edge of the seat is closer to the center of gravity, heightening the risk of the individual falling forward out of the wheelchair during normal operation of the chair. If the seat is too deep, circulation may be restricted due to pressure on the poples and the upper posterior areas of the calves, which may also cause skin irritation.
The distance from the heel to the underside of the thigh provides the basis for determining both footrest height and seat height. The footrest should be high enough to allow safe traverse of curves, thresholds and uneven surfaces. The seat should be high enough above the foot rest to allow the individual's weight to be distributed along his thighs and buttocks, but not so high above the ground or floor that the individual's knees preclude the use of standard tables. If the seat height is too low, there will be undue pressure on the ischium, along with potential problems associated therewith.
Armrest height is another basic dimension of a wheelchair, and is based on the distance from the bottom of the buttocks to the outer bend of the elbow. If the armrest is too high above the seat, use of the armrest will push up the shoulders causing muscle fatigue, prompting many individuals not to use the armrest, with the resulting loss of stability in the sitting position. If the armrest is too low, the individual may stoop or slump to rest his forearms on the armrest, which can be unduly tiring, may effect poor balance and affect breathing.
The final dimension mentioned is back height. The measurement on which to base the back height depends on the trunk control of the individual. If normal or minimal trunk support is needed, the dimension is based on the distance from the bottom of the buttocks to under the axilla, with the arms fully extended parallel to the ground. If full trunk support is needed, the dimension is based on the distance from the bottom of the buttocks to the shoulders, neck or mid-head level, depending upon the required level of support.
It has heretofore been recommended that an individual be measured, with a tape measure, for example, in a sitting position on a standard hard back chair. In this manner, the individual is in a position as closely resembling his desired position as has been heretofore possible. Being measured for a wheelchair can be a time-consuming and a sometimes painful experience for an individual, depending upon his condition. When the individual exhibits tone problems, it is usually recommended that the measurements for seat depth taken in the sitting position be augmented with measurements taken in a supine position due to the posterior tilt of the pelvis during uncorrected sitting. Generally, the individual is placed on his back on a firm surface. While one person holds the individual's legs in the optimal position (hip flexion - 90%, knee flexion - 90%). Another person measures the distance from the back of the buttocks to the back of the knee. Putting an individual in a supine position to take measurements can be difficult, especially if he is a large adult. Getting the individual out of the supine position maybe next to impossible.
In addition to the basic measurements mentioned by Everest and Jennings, Inc. in Measuring The Patient, there are other considerations which must be taken into account when prescribing a wheelchair. Some of the measurements and conditions are best noted when the individual is seated in a wheelchair having the proper basic dimensions mentioned above, which often means that the wheelchair must be made in two stages--the basic wheelchair is constructed, then special cushions and securing devices are added once the individual has tried out the basic wheelchair. This increases the time of manufacture of the wheelchair, which can be particularly disadvantageous when the individual is still growing, or when the individual's condition is changing rapidly. There are cases in which an individual's condition has changed so much between prescription and delivery that the wheelchair is obsolete before being used. Examples of factors which can best be measured or determined when an individual is seated in a wheelchair having the proper basic dimensions include body alignment, posture, pressure and shear.
In addition to the problems of accurate measurement and proper determinations of all conditions affecting the prescription of a wheelchair, many individuals are also faced with the task of convincing a third-party payer, such as an insurance company, that a custom-fitted wheelchair is not only desirable, but also necessary to prevent further complications which could necessitate hospitalization. Some insurance companies want to be assured that the custom wheelchair will in fact be advantageous; all too often this can only be shown once the wheelchair in constructed--a situation in which many individuals have no recourse other than to buy the custom wheelchair themselves, then be reimbursed by the insurance company once the company is convinced that the wheelchair is a necessity. For individuals with limited financial means, even this manner of recourse may be impossible.